1. Field of Technology
The present invention relates to a product identification system using IC tag units, and relates more particularly to an identification system for optical discs having an affixed IC tag unit. The invention also relates to a digital content management system for using IC tag units to manage digital content recorded to optical discs.
2. Description of Related Art
Technologies enabling on-line management of products using small electronic circuit units called RF tags or IC tags affixed to individual products are known from the literature. As the cost of these IC tag units has dropped, however, the range of potential applications has increased significantly, leading to a rapid rise in demand.
These IC tag units have a loop antenna, and power sufficient to drive the IC unit is supplied from the antenna as taught in Japanese Patent Laid-open Publication No. H11-59040. Power is typically supplied to the IC tag unit by means of electromagnetic induction of strong electromagnetic waves emitted from an external source to the antenna as taught in Japanese Patent Laid-open Publication No. H10-242893. The dc voltage required for IC operation is acquired by rectifying and smoothing the ac current output from the antenna as taught, for example, in Japanese Patent Laid-open Publication No. H11-215026.
IC tags are primarily used to identify the products to which they are affixed, and the IC tag unit contains ROM for storing information enabling this identification (that is, ID information). When power is supplied to the IC tag this ID information is read and output from the antenna after passing through a modulation and transmission circuit also disposed in the IC tag. Modulation methods include phase shift keying (PSK) as taught in Japanese Patent Laid-open Publication No. 2000-332842.
Japanese Patent Laid-open Publication No. 2002-163613 and Japanese Patent Laid-open Publication No. 2003-317048 also teach using this IC tag technology for identifying and managing individual optical discs. This technology enables encrypting commercial content downloaded for a fee to an optical disc using this ID information as the encryption key, and can thus prevent unauthorized duplication of the downloaded content to another optical disc.
A problem with the foregoing prior art is that cost is a major obstacle to actually using IC tags to individually manage optical discs. More specifically, while the cost of the IC tag units continues to drop, a separate device is needed to produce the strong electromagnetic waves needed to supply power to the IC tag units, and these devices are expensive and large. On the other hand, the cost of the CD-ROM and DVD-ROM drives that are typical optical disc drives is also dropping, and adding such a device for producing electromagnetic waves is completely unrealistic considering current trends in the optical disc drive market.
In addition to this problem of cost, generating strong electromagnetic waves means that an electromagnetic shield is also required, thus creating structural design problems.
DVD drives have also become small enough to fit inside a notebook computer, and further increasing the size of the DVD drive is thus also not practical.
A further problem is that DVD drives with a recording function (such as DVD-RAM drives) are typically used as recorders for recording TV programs, and the electromagnetic waves needed for IC tag unit operation can easily affect reception of TV programs.
An object of the present invention is therefore to provide a product identification system for identifying products bearing an IC tag unit by supplying power to the IC tag unit without using an expensive electromagnetic wave generator requiring measures for protection against electromagnetic interference.